Question

What role do proteins and chemical secretions on the stigma surface play in pollen-pistil interaction?

Options

• They prevent water absorption by the pollen grain

• They directly form the pollen tube structure

• They act as recognition molecules that determine pollen compatibility

• They dissolve the pollen coat entirely

Answer 1

The stigma surface contains special proteins and chemical secretions that function as recognition molecules. These interact with chemical components on the pollen grain surface to determine whether the pollen is compatible or incompatible with the pistil, thereby controlling acceptance or rejection.